In 2007 Red Hat stood on top of the Linux kernel contributor list with room to spare. At 12.7 percent of the Linux kernel contributed by Red Hat (measured in terms of lines changed), IBM was the runner-up at a comparatively distant 5.9 percent. In 2008, Red Hat slipped a little but maintained the top spot (11.2 percent), with Novell making a burst into second place at 8.9 percent.
In 2009, things get more interesting, with Intel making a serious challenge to claim the top spot in Linux kernel contributions.
Red Hat, Novell, and IBM all have substantial software businesses, with heavy investments in Linux, so it makes sense that they'd contribute heavily to the Linux kernel. But according to new data Jonathan Corbet of LWN.net announced at the Ottawa Linux Symposium on Wednesday, Intel has surged from 2.3 percent in 2007 to 4.1 percent in 2008 to 6.9 percent in 2009.
rest here